Support requested in this application is for the ongoing and expanding participation of the Division of Radiation Oncology of the University of Califfrnia in San Francisco in the activities of the Radiation Therapy Oncology Group. Comprised of three hospitals, Moffitt, Mt. Zion and Franklin, the Division is staffed by eleven full-time faculty members, treating 2000 new patients per year. The Division has participated in the Group since 1972, entering approximately 100 cases into various Group studies from Moffitt Hospital alone. The principal investigator is a member of the Executive Committee and Chairman of the Radiobiology Committee of the RTOG and all staff members serve on working parties. The group has produced protocols for head and neck cancer, non-Hodgkin's lymphoma, brain metastasis, and hypoxic cell sensitizers, as well as providing input into other protocols. Support through this application will allow RTOG participation by the entire Division leading to the accession of at least 150 new patients per year into protocols. Extensive continuing research into high LET, chemical and thermic modification of radiation effects is expected to lead to innovative protocols and, correspondingly, to increased accession of patients into studies sponsored by RTOG.